1. Field of the Invention
The present invention pertains to high strength reactive materials and methods for their production, especially high strength materials having maximum stresses and strains that exceed those heretofore obtained with conventionally fabricated energetic materials. The present invention also relates to warheads comprising the high strength energetic materials.
2. Description of the Related Art
Various military warheads are equipped with a liner or inner sheath comprised of a reactive material. In principle, upon impact these warheads are intended to deliver kinetic energy and chemical energy from the reactive material. The reactive material is intended to fragment, react and release energy (chemical) as a result of the high temperature and pressure (shear) when the warhead impacts its target. The reactive fragments provide additional means for threat destruction.
At present, however, there has been a need for a sufficiently robust reactive material that is inert during storage, but which has significantly improved strength characteristics. Reactive materials produced by conventional methods have been found to possess inadequate tensile strength and to be characterized by poor elongation at break.
It would be a significant advancement in the art to discover a reactive material comprised of a fluoropolymer and a particulate metal or metalloid which has a tensile strength greater than 1800 psi and a strain (elongation at break) of greater than 30%, and a method for its production.
Metallic particles such as aluminum, zirconium, titanium, and magnesium are energetic fuels that, if distributed in a fluoropolymer, would establish an excellent reactive material. However, known methods of distributing metal particles into fluoropolymers involve the oxidization of these particles, which significantly reduces their energetic capacities. For example, U.S. Pat. No. 2,961,712 to Davis discloses a method of making filled polytetrafluoroethylene products in which a metallic filler, such as aluminum powder, is inter-dispersed and precipitated in a dispersion of the polytetrafluoroethylene, which is then dried and sintered. The sintered mixture is broken up into powder. The sintered powder is then mixed with another polytetrafluoroethylene dispersion, precipitated, and subjected to a second sintering process. Davis characterizes its fillers as substantially inert, most probably due to the use of an oxidizing atmosphere during preparation and sintering of its energetic particles. Other U.S. patents disclose the use of water or aqueous solutions for dispersing metal and metalloid particles in a fluoropolymer. However, water generally functions as an oxidizing agent and, in the presence of some metals, such as aluminum, can cause the release of hazardous amounts of hydrogen gas.